78 lines
1.6 KiB
Rust
78 lines
1.6 KiB
Rust
use crate::{bin::*, crc::*};
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use std::{fs::File, io::prelude::*};
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#[derive(Clone)]
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#[derive(Debug)]
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pub struct PngChunk
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{
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pub typ: Ident,
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pub dat: Vec<u8>,
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}
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#[derive(Clone)]
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#[derive(Debug)]
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pub struct PngFile
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{
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pub chnk: Vec<PngChunk>,
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}
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impl PngFile
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{
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pub fn new(b: &[u8]) -> Result<PngFile, &'static str>
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{
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if &b[0..8] != b"\x89PNG\r\n\x1a\n" {return Err("invalid header")}
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let mut chnk = Vec::new();
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let mut p = 8;
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loop
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{
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let len = b.c_u32b(p )? as usize;
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let typ = b.c_iden(p+4 )?;
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let crc = b.c_u32b(p+8+len)?;
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if crc32(&b[p+4..p+8+len], 0) != crc
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{return Err("invalid CRC in chunk")}
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chnk.push(PngChunk{typ, dat: b[p+8..p+8+len].to_vec()});
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if typ == *b"IEND" {break} else {p += len + 12}
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}
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Ok(PngFile{chnk})
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}
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pub fn write(&self, fp: &mut File) -> std::io::Result<()>
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{
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fp.write_all(b"\x89PNG\r\n\x1a\n")?;
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for c in &self.chnk
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{
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fp.write_all(&d_u32b(c.dat.len() as u32))?;
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fp.write_all(&c.typ)?;
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fp.write_all(&c.dat)?;
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fp.write_all(&d_u32b(crc32(&c.dat, crc32(&c.typ, 0))))?;
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}
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Ok(())
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}
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pub fn has_chunk(&self, t: Ident) -> bool
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{
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for c in &self.chnk {if c.typ == t {return true}}
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false
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}
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pub fn find_chunk(&self, t: Ident) -> Option<usize>
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{
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for i in 0..self.chnk.len() {if self.chnk[i].typ == t {return Some(i)}}
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None
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}
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pub fn chunk<Ret, F: Fn(&[u8]) -> Ret>(&self, t: Ident, f: F) -> Option<Ret>
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{
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for c in &self.chnk {if c.typ == t {return Some(f(&c.dat))}}
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None
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}
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}
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// EOF
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